Designation: D 5641 94e1

AMERICAN SOCIETY FOR TESTING AND MATERIALS 100 Barr Harbor Dr., West Conshohocken, PA 19428 Reprinted from the Annual Book of ASTM Standards. Copyright ASTM

Standard Practice for

Geomembrane Seam Evaluation by Vacuum Chamber1

This standard is issued under the xed designation D 5641; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

e1 NOTEThe title was corrected editorially in June 1995.

1. Scope 1.1 This practice covers procedures to perform nondestructive quality control testing described in Practice D 4437 and D 4545 for evaluating the continuity of all types of geomembrane seams using the bubble emission or vacuum chamber method. 1.2 The technique described in this practice is intended for use on geomembrane seams, patches, and defects. 1.3 The values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are provided for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: D 4437 Practice for Determining the Integrity of Field Seams Used in Joining Polymeric Flexible Sheet Geomembranes2 D 4439 Terminology for Geotextiles2 D 4545 Practice for Determining the Integrity of Factory Seams Used in Joining Flexible Sheet Geomembranes2 E 515 Test Method for Leaks Using Bubble Emission Techniques3 2.2 E.P.A. Documents: EPA/600/2-88/052 Lining of Waste Containment and Other Impoundment Facilities, NTIS PB89-129-6704 EPA/530/SW-91/051 Inspection Techniques for the Fabrication of Geomembrane Field Seams4 3. Terminology 3.1 Denitions of Terms Specic to This Standard: 3.1.1 geomembrane, nan essentially impermeable geosynthetic composed of one or more synthetic sheets. (See1 This practice is under the jurisdiction of ASTM Committee D-35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes. Current edition approved Nov. 15, 1994. Published January 1995. 2 Annual Book of ASTM Standards, Vol 04.09. 3 Annual Book of ASTM Standards, Vol 03.03. 4 Available from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.

Terminology D 4439). 3.1.2 seam, nthe connection of two or more pieces of material by mechanical, chemical, or fusion methods to provide the integrity of a single piece of the material. 3.1.3 vacuum chamber, na device that allows a vacuum to be applied to a surface. 3.1.3.1 DiscussionIn geomembranes, typical seams would include adhesive bonded, bodied chemical fusion welds; chemical fusion welds; dielectric; dual hot wedge; llet extrusion; at extrusion; hot air; single hot wedge; and ultrasonic. (See EPA/530/SW-91/051.)NOTE 1For denition of other terms used in this practice, refer to Terminology D 4439.

4. Summary of Practice 4.1 The basic principle of this practice consists of creating a pressure differential across a seam and observing for bubbles in a lm of foaming solution over the low pressure side, within the vacuum chamber. The vacuum chamber has a viewing port that allows observation of the seam area being tested. The foaming solution is applied to the surface to be tested and the vacuum chamber is placed over the test area. As the chamber is held rmly in place, vacuum is applied. Air leakage through aws in the test area cause bubbles in the foaming solution that may be observed. 5. Signicance and Use 5.1 This practice is a nondestructive evaluation intended to be used for quality control purposes during factory or eld seaming of geomembranes. 5.2 This practice may also be used to evaluate geomembrane panels for holes that penetrate the entire thickness of material. Limitations on the test practice are that it may not be suitable for uneven or curved surfaces, thick seams, seams in corners, and thin extensible geomembranes. 6. Apparatus 6.1 Vacuum PumpThe vacuum pump shall be fuel or electric powered and capable of sustaining the required vacuum for the duration of the test. 6.2 Vacuum GageThe vacuum gage shall be capable of registering, as a minimum, to 70 kPa (10 psi) in increments of 5 kpa (34 psi).

D 56417.3 Wet an area immediately adjacent to and including the geomembrane seam or test area measuring approximately twice the width and length of the vacuum chamber with a foaming solution. 7.4 Place the vacuum chamber over the wet area of the geomembrane such that the gasket is in complete contact with the geomembrane surface, and the test area is centered under the viewing port. 7.5 Apply a normal force to the top of the vacuum chamber to effect a seal and open the vacuum valve. 7.6 Ensure that a leak tight seal is created between the vacuum chamber gasket and the geomembrane material. For most cases, a minimum vacuum of 28 to 55 kPa (4 to 8 psi) as registered on the vacuum gage should be appropriate. 7.7 With the vacuum applied, maintain the normal force and observe the geomembrane seam or test area through the viewing port for bubbles resulting from the ow of air through defects in the seam. The vacuum should be held over the test site for a duration of not less than 10 s. If the vacuum cannot be held for the minimum 10 s, the test area shall be marked as untested. It is essential that the viewing port remain clean at all times to facilitate unobstructed viewing. 7.8 If bubbles appear on the geomembrane seam, turn the three-way vacuum valve to vent the chamber and remove the vacuum chamber from the seam. The defective area should then be marked for repair. 7.9 If bubbles do not appear through the geomembrane seam within the specied dwell time, turn the vacuum valve to vent the chamber and remove the chamber from the seam. 7.10 Move the vacuum chamber to the adjoining portion of the seam or test area overlapping the previously tested area by a distance no less than 10 % of the minimum chamber length or at least 50 mm (2 in.), whichever is the greater and repeat the procedure until the entire seam has been tested. 8. Report 8.1 Report the following information: 8.1.1 Identication of the geomembrane material, including type of polymer, source, thickness, reinforced or nonreinforced sheeting, seaming system used, ambient temperature, seam tested, seam width, date of seam fabrication, and date of seam evaluation, and results of seam evaluation,NOTE 4The intent of the form is not to imply that each VCT is to be recorded on said form.

FIG. 1 Vacuum Chamber

6.3 Calibration and AdjustmentThe calibration of the vacuum gage shall be checked and adjusted periodically, and routinely at a minimum of once every twelve months. 6.4 Foaming SolutionThe foaming solution shall be premixed with water at a ratio conducive to the formation of bubbles. It shall be dispensed by spray, brush, or any other convenient means. The foaming solution shall be compatible with the geomembrane.NOTE 2If the component to be tested has parts made of polyethylene or structural plastics, the test uid must not promote environmental stress cracking (E.S.C.). (See Test Method E 515.)

6.5 Vacuum ChamberThe vacuum chamber shall have an open bottom and a clear viewing panel on top. It shall be an appropriate and convenient size and shape, made of rigid materials and equipped with a vacuum gage, valve, and soft pliable gasket around the periphery of the open bottom (see Fig. 1).NOTE 3Vacuum chamber equipment may be obtained from the suppliers given in Footnote 5.5 These suppliers are cited only for convenience and no commercial endorsement is expressed or implied by incorporation into this practice.

7. Procedure 7.1 The area of the seam to be evaluated should be clean and free of soil or foreign objects that might prohibit a good seal from being formed between the vacuum chamber and the geomembrane. 7.2 Energize the vacuum pump.

8.1.2 Documentation of the typical vacuum pressure and hold duration and latest pressure gage calibrations, 8.1.3 Identication of the location and approximate size of all defective areas, and 8.1.4 Identication of foaming solution used for the test and if different types were used, the location of use for each type. 9. Keywords 9.1 bubble emission testing; geomembrane; nondestructive testing; seam; testing; vacuum; vacuum chamber

FIG. X1.1 Evaluation Form

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